Since adopting disposable medical instruments, a large number of waste instruments bring on the problem of environment pollution. Furthermore, the utilized instruments with needles frequently puncture-wound the medical workers, resulting in that the virus or bacteria carried by the bodies of the patients can infect the medical workers and causing the medical workers to be infected diseases even to be dead. These events are often heard in the worldwide. Currently, the problem of the unexpected puncture-wound is attended more and more due to the susceptibility of AIDS, hepatitides and other serious hematopathies.
Thus it can be seen that puncture-wounding the medical workers by the needle heads of the instruments with needles possesses huge danger. Accordingly, numerous apparatus have been provided for eliminating or decreasing this danger. At present, these apparatus can be produced in theory, but actually, many apparatus fail to adapt to be manufactured economically and reasonably in mass production and/or in low cost mainly because the adopted technologies and processes are too complex, for instance, existing the problem of molding tolerance.
U.S. Pat. No. 5,348,544 granted to Sweeney, et al., on Sep. 20, 1994 (simply referred to as “Sweeney's”) has opened an injector apparatus involving a shield. The shield is slid by manual operation along the needle-head duct, from the position where it is near the operator to the far position where the needlepoint is covered. The apparatus includes an articulated arm, which protrudes from the needle-head duct and is movable away from the operator for self-folding, so that the shield protrudes and cover the needlepoint. A metal clip blocks the contact of the needlepoint. In addition, it further opened a substituting embodiment, wherein a spring assists the manual operation. The company Becton Dickinson located in Flankling Lake City of N.J. has sold an injector apparatus designed on the basis of the Sweeney's patent, which utilizes three separate parts (two molded parts and one metal clip) for moving the shield. Once the apparatus protrudes in order to cover the needlepoint, it is hard to be resetting. Therefore, the needle head is difficult to continue to be used. Furthermore, the articulated arm needs to be started at the area where the needle head is located and includes some parts. These parts will hinder the operator to watch the position where the needle shall penetrate.
U.S. Pat. No. 5,246,428 granted to Donaldw. Falknor (simply referred to as “Falknor's”) on Sep. 21, 1993 has opened an injector apparatus involving a covering part, which can be released automatically to protrude in direction away from the operator, so as to cover the needle head. This apparatus includes a locking mechanism, which can be switched manually between the unlocking position and locking position, so as to expose the needle head for using and locking the covering part on the needle head. Of course, the positions of the locking mechanism provide the visual indication of the safety condition of the apparatus (whether the latch is fastened). However, this locking mechanism is a sole safety mechanism and the position indication thereof may be “lost” in the tensional circumstance. When the locking mechanism is at the unlocking position, if the front end impacts certain areas of the body, it will occur that the areas contact the needle head. In addition, the covering part can cover a portion of the connected injector body before the covering part wholly protrudes. Even if the covering part is made of transparent material, it is possible that the indicating mark of volume metering on the injector body is difficult to be red out accurately when the injector is used in the case of titration.
U.S. Pat. No. 5,256,153 granted to Lawrence W. Hake (simply referred to as “Hakes'”) on Oct. 26, 1993 has opened an injector apparatus, which includes a shield slid by manual operation. The shield is located on the injector body in the process of medical treatment using the medical needle head of the injector and usually slides into the position where the needle head is protected in the direction away from the operator after finishing this course. The operators utilizing this apparatus usually complain that it is difficult to clearly view the metering indication mark when the shield is located on the injector body and there is a danger of unexpected puncture wound made by the needle head when the shield moves in direction away from the operator for covering the needle head. Furthermore, when the shield covers the needle head, it is hard to determine if the shield is in locking condition or unlocking condition, resulting to the possibility of unexpected puncture wound made by needle head.
U.S. Pat. Nos. 5,139,489 and 5,154,285 granted to William H. Hollister (simply referred to as “Hollister'”) respectively on Aug. 18, 1992 and Oct. 13, 1992 have opened a needle head protecting apparatus, which can be applied in a assembly of cuspidal needle head having two ends or simpler single needle head system. This protecting apparatus includes a generally rigid shell, which flexibly join with a container used in a vacuum test tube sampling system or a needle head casing. When operating this protecting apparatus, the rigid shell pivots to the position where the exposed needle heads of the assembly of cuspidal needle head having two ends are joined and is reliably fixed on the exposed needle heads. One of the main defects existing in the Hollister's needle head protecting apparatus lies in the length size and position of the rigid shell. The length size and position of the rigid shell causes the inconvenience when some assemblies or systems are used in process of medical treatment, as considered by some peoples. The second defect is that it is need to either pivot the shell to join the needle head by two hands, or seek out and utilize a certain stably supporting surface to withstand the shell when the needle head pivots into the shell. In a structure of a currently sold product, a retainer of a certain integral container of the Hollister's apparatus includes two molded parts, which can make the shell pivot as far as possible to the position where the process of medical treatment is not hampered. This design needs five molded parts including a needle head assembly, which can be discarded.
U.S. Pat. No. 5,823,997 granted to David L. Thorne (simply referred to as “D L. Thorne'”) on Oct. 20, 1998 has opened a collapsible scabbard for a needle head, in which the scabbard is folded around a medical needle head, allowing to operate the needle head in process of medical treatment. The scabbard in a point away from the sharp needle end is hinged on a structure, such as the needle head casing or bloodletting barrel. The needle end is enveloped last, so as to protect the operator. At the end of the process of medical treatment, the scabbard is unfolded and protrudes in the direction toward the needle end away from the structure, so as to envelop the needle head and the cuspidal needle end thereof, which the operator can not contact. According to the description made by D L. Thorne, an important object of the apparatus is to provide a scabbard, which is collapsible for use in the process of medical treatment adopting medical needle head and can be unfolded to join the needle head to form a structure of a generally rigid needle head casing, so as to prevent unexpected contacting the cuspidal needle end. But there are two defects existing in this apparatus. One defect lies in that its structure is more complex and machining mold and molding is too difficult when the bloodletting barrel or needle head casing is integrally mold-formed, the costs thereof is hard to be accepted. The second defect lies in that this apparatus fails to meet the requirement of detachability and interchangeability of the medical needle. As we usually known, the medical needles in a clinical use often need repeatedly detaching and installing. For example, the injector needs to change the needle head when dispensing and human injecting. This requires that the medical needle shall possess the detachability and interchangeability. The common medical needles possess this characteristic, but in the designs of safe medical needles or instruments, in order to meet the function for protecting the needle, the detachability and interchangeability of the medical needle is lost. This defect exists not only in the opened patents of Sweeney, Falknor, Hake, Hollister, and D L. Thorne, et al, but also in the most of the safe types patent designs. This is the one of the important reasons why such more patent designs are hard to be commercialized.
The U.S. Pat. No. 6,254,575 granted to Gale H. Torme (simply referred to as G H. Thorne's) on Jul. 3, 2001 has also opened an improved shield of a collapsible needle head, which is similar to the D L. Thorne's, but possesses the detachability and interchangeability in respect to the injecting needle. The defect thereof lies in that the structure is too complex, not only it is difficult to molding-process, but also the volume size thereof is too large due to having the requirement for the length after spreading the collapsible shield, being difficult to use in the hollow medical needle head apparatus of the transfusion device, the cannula indwelling needle.
Therefore, though the above apparatus in the prior art can prevent that the instruments with needles stab the operator after use, it is difficult to be widely used in the medical field due to the complex structure and the expensive cost of manufacture thereof. In addition, lacking function of the detachability and interchangeability between the apparatus and the common medical needles leads to high use cost and makes use of these apparatus be restricted.